1. The document discusses optimizing the form of wind turbine blades for maximum momentum through varying the pitch and chord of the blades using computational fluid dynamics (CFD) software. 2. The author uses FRIENDSHIP SYSTEMS' optimization software FFW to vary the pitch and chord of a blade model and couples it with Star CCM+ CFD software to analyze different blade designs. 3. The optimization evaluates 100 different blade designs varying pitch and chord and identifies designs that minimize momentum to determine the optimal blade form for maximum energy generation.

1. http://www.friendship-systems.com/forum/
Wind Blade Form Optimization for Maximum
Momentum
It was early morning on the way to the FSYS office.
Suddenly the handy began ringing and I intuitively noticed that it is very urgent thing.
Yes of course it was.
He was a staff of a symposium that will be held in two weeks in Korea.
The main topic of the symposium was about Wind Energy and his request was my participation as a
lecturer for a leading edge technique session.
I was about to answer "NO" very politely since the schedule was already full of other issues. But it was he
concluded the conversation before my negative reaction.
"Thanks MR Park, I trust you. Bye."
Ok, let's make it done. I have tools and colleagues to support me tightly !
Check list.
1. Which Form ? = Not all wind power plant but just a blade.
2. How to vary ? = Pitch and Chord (Why? Why not!)
3. CAD = FFW
4. Optimizer = FFW
5. CFD = Star CCM+
6. Software Coupling = FFW.
It seemed not bad and I pushed the project straight forward.
Blade model
I used the blade example model in FFW directly.

2. http://www.friendship-systems.com/forum/
The blade model is parameterized.
Pitch, Thickness, Chord and the radial position are defined with continuous functions.
Camber, Camber Position and Blade length are defined with constant values.

3. http://www.friendship-systems.com/forum/
Pitch Variation
Pitch value is controlled by pitch function in the 3D idea.
http://www.youtube.c...bed/Au385eEK5Ow
Chord Variation
In the same fashion with pitch variation, it could be seen in the movie below.
http://www.youtube.c...bed/_TBgNrISe4Q
Analysis
This is very critical phase to decide how to perform CFD calculation.
FRIENDSHIP SYSTEMS has very cooperative partner of CD-Adapco Nuernberg Germany.
I made contact with them and asked them for Mesh and Java-Macro of the blade geometry.
The kindest CD-Adapco support team took care of it and made me feel comfortable.
All what I did to them were to give the information about :
 Wind Speed 11 m/s
 RPM 500
 Geometry of blade in STL file format.
What they gave me back were :
 JAVA Macro file that create the reasonable surface and volume meshes for the given STL file.
 Sim file, i.e. Simulation file, which will run the java macro file in STARCCM+.

4. http://www.friendship-systems.com/forum/
Coupling
Let FFW know where the Java macro file is. Then FFW will, JUST ONCE, import the file and recognize as
the code embedded in itself. And Let FFW know where the result file (CSV file format this case) is. Then
FFW will, JUST ONCE, import the CSV file and recognize what is the final result value of the CFD analysis.
Optimization Condition
Design Variables
Pitch Control Point [-0.5,1]
Chord Control Point [0.1, 0.5]
Objective Value
Momentum ( Multiply -1 to the result value due to the minimization algorithm)
Design variants number
100 designs
Search Engine
Sobol Engine for DoE.

5. http://www.friendship-systems.com/forum/
The distribution of searching points by Sobol
The distribution of the objective value for each design.

6. http://www.friendship-systems.com/forum/
Typically chord values have periodic distances between the minimum of objective vales. But the pitch
values show very distinguishing valley shape for the minimum objective. One interesting phenomenon is
that pitch variation has another baby range of minimization but I ignored it this time to research the
reason more deeply due to the time limit.

7. http://www.friendship-systems.com/forum/
Final result
Sorry that I did not create the beautiful pictures of flow and pressure distribution as post-processing. The
allowed actual working time for this speedy project was just 3 days. Without the effective support and
cooperation from CD-Adapco team this could not be done in the reasonable time. (Thanks again Martin!)
I was happy to be able to help the customer to manage the important session successfully and also
pleased to hear the applause from the audience.
ㅁ